Process employing catalyst coated yarn processing rolls

ABSTRACT

A surface for contacting a moving finish coated textile yarn at elevated yarn treatment temperatures in the presence of oxygen. The surface is characterized by irregular, rounded nodules which bears within its interstices finely-divided catalyst particles that will catalyze oxidation of finish deposits that form on the surface at the yarn treatment temperature. The time between periodic cleaning cycles is greatly lengthened with attendant savings in labor and loss of production.

United States Patent 11 1 1111 3,849,177 Fernandes Nov. 19, 1974 [54] PROCESS EMPLOYING CATALYST 3,266,477 8/1966 Stiles 252/477 R COATED YARN PROCESSING ROLLS tee [75] Inventor: Ha old Fe a de e 3,486,928 12/1969 Rhoda et al 117/71 R 3,676,188 7/1972 Silverman et a1. 117/71 R [73] Asslgnee' gg ig gfix?s z% 3,787,229 1/1974 Rudness 117/1284 [22] Filed: June 1972 Primary Examiner-Charles E. Van Horn 21 App]. 2 ,000 Assistant Examiner-Michael W. Ball [52] US. Cl. 117/71 R, 29/132, 117/130 R, [57] ABSTRACT 117/160 R, 242/157 R, 252/477 R 1 51 1m. 01 B65h 57/00, B0 1 j 9/00 A Surface Contact a mvmg fimsh mated exme of Search... R M O yarn at elevated yarn treatment temperatures in the 117/119 6 130 R 160 47 i 11 presence of oxygen. The surface is characterized by R 102 19 6 132 E 252/81 irregular, rounded nodules which bears within its in- 477 2 7 68/6 terstices finely-divided catalyst particles that will cata- 29/132. m lyze oxidation of finish deposits that form on the surface at the yarn treatment temperature. The time be- [56] References Cited tween periodic cleaning cycles is greatly lengthened with attendant savings in labor and loss of production. UNITED STATES PATENTS 3,080,134 3/1963 England et a1. 117/64 R 5 Claims, No Drawings PROCESS EMPLOYING CATALYST COATED YARN PROCESSING ROLLS BACKGROUND OF THE INVENTION This invention is related to the field of hot-processing textile materials. More particularly, it relates to an improvement in means for treating textiles which have an organic finish on them, in which the textiles are in contact with hot metal surfaces.

There are many processes in which textiles are brought in contact with hot metal surfaces. Fabrics are conventionally heat set while passing over rolls in an oven. Tire cord is conventionally dipped and hot stretched in an oven. Warp yarn is normally coated with a size which is then heated to dry it. In the course of manufacture, synthetic filaments are often drawn or relaxed while in contact with heated metal surfaces, or while in an oven. In most of these processes, the filaments of the textile have a coating of organic material such as tire cord adhesive, size or yarn lubricating finish which may be rubbed off onto the metal surface with which they come in contact. Whether the metal surface is itself a source of heat, as is a conventional hot plate or hot tube such as are often placed in the draw zone, or whether the surface by yarn carrying rollers driven by external motors and housed in an insulated chest supplied with recirculating hot air, these deposits of organic material tend to form insoluble varnish on the roll surface. As these deposits accumulate, they cause yarn breakage. Consequently, a cleaning routine must be established, with attendant labor costs and interruption of production.

The prior art has recognized this problem and has tried to solve it by mechanical methods. Au in U.S. Pat. No. 3,068,530 passes yarn in helical wraps around a heated pipe. While in use, the pipe is slowly rotated so that such deposits that form are worn away by the running yarn. Marlborough et al. in U.S. Pat. No. 3,483,593 solve the same problem in a similar way by traversing the yarn to and fro in its path across a hot plate.

Although these expedients have provided some improvement when using stationary metal surfaces, they wont work when the yarn and metal surface move at the same speed as the rollers do which are needed in hot stretching ovens for tire cord or in hot chests where yarn is drawn, annealed or relaxed, for example, in the hot chest shown by A. N. Good in U.S. Pat. No. 3,31 l,69 1.

DEFINITION OF THE INVENTION The improvement of this invention is obtained in a process for heat treating a moving filamentary structure having a coating of a textile finish containing oxidizable organic components, wherein the structure is contacted with a surface at elevated temperatures within the range of about 100C. up to the melting point of the structure in the presence of oxygen. The improvement is obtained by using a surface characterized by irregular, rounded surface nodules, which bears within its interstices a catalytic amount of finelydivided platinum, palladium or mixtures thereof, whereby any finish components transferred to the said surface are oxidized to volatile by-products and harmless carbonaceous residues at the filament treatment temperature.

The surfaces which are to be impregnated with the catalyst must be clean and free from grease; a solution of soluble salt of the catalyst and a reducing agent is applied to a warm surface (e.g., a draw roll), the roll is heated to dry and reduce the catalyst to finely-divided platinum and/or palladium particles; the coating step may be repeated to provide a coating having about 0.03 to about 0.5 gm. of .catalyst per sq. ft. of yarn contacting surface.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred surface to which the catalyst is applied is the oxide-coated surface invented by England & Spellman in U.S. Pat. No. 3,080,l34 which provides a low friction, abrasion-resistant surface by flame coating a metal yarn-contacting surface of a yarn handling apparatus with a refractory oxide to produce a ceramic coating thereon. For reasons of mechanical strength or adequate heat transfer, it is frequently necessary to provide apparatus consisting primarily of metal. The ceramic coating is then lightly polished with abrasive, such as fine emery cloth, to produce a nodular surface having a surface roughness of to 250 root mean square (rms) microinches, as measured with a conventional stylus-type measuring instrument reading directly in rms microinches, the surface being free from sharp peaks. The preferred refractory oxides used to provide this coating are Cr O and AI O The oxide coating is especially desirable for use in combination with the platinum and/or palladium catalyst because these oxidation catalysts are conventionally used when deposited on a refractory oxide. Moreover, the roughness of the surface permits deposition of catalyst in the interstices, between the nodules, so that it is not abraded away by the running yarn.

Indeed, for some uses it is not necessary to have a ceramic-coated surface on which the catalyst is deposited. The use of polished steel, which is sand-blasted and then chromium-plated, provides a nodular, low friction surface, such that some catalyst can be retained in the interstices between the nodules where it can exercise its catalytic function without being abraded away by the yarn.

It is surprising that the oxidation catalyst is effective in eliminating the organic residues at temperatures below the melting point of synthetic fibers. Conventionally, such catalysts are used at temperatures of over 400C, well above the melting point of all melt-spun fibers. In addition to platinum and palladium, other metals known to catalyze decomposition of organic materials at moderate temperatures may be employed, singly or, in comobination. Typical metals are rhodium and ruthenium; the use of osmium and iridium will generally be uneconomical.

Any water soluble platinum or palladium salt can be used to prepare the treating solution for application to the metal surface. The platinum salts should be free from foreign ions which are not removable by volatilization during the reduction treatment, or by washing subsequently. Nitrate and nitrite salts of platinum and palladium are especially useful; the chloroplatinates and similar halogen containing compounds may have a corrosive effect which is harmful to metal parts.

Water soluble reducing agents such as hydrazine hydrate, hydroxylamine and aldehydes such as formaldehyde are useful, although it is quite possible to apply a solution of platinum salt to the metal surface, dry and reduce in an atmosphere of hydrogen.

Preparatory to applying the catalyst, the metal surface must be clean and free from oil or finish deposits. lf newly coated with alumina, the surface may have the catalyst applied directly. If the article has been used in yarn production, it should be cleaned to be sure that no oil or finish remains to prevent the treating solution from wetting the surface. A very thorough cleaning method is to boil the article, such as a roll, in synthetic detergent solution, followed by rinsing and heating in a furnace for one half hr. at 450C. Ordinarily, such thorough cleaning is not required, especially when reactivation of catalyst is all that is required.

If organic material deposits are allowed to build up on heated spinning equipment such as draw rolls, the residue will ultimately become visible as a varnish-like deposit. This deposit reduces yarn quality to an intolerable level. By yarn quality" is meant threadline breaks, broken individual filaments and yarn wraps built up on the rolls. It has been found necessary to clean rolls in commercial use every 3% days; otherwise, yarn quality deteriorates rapidly to an intolerable level after about 4 days. Yarn quality improves immediately after this step is taken. This procedure has now become unnecessary in view of the instant invention.

When catalyst coated rolls have been in commercial use for 6 months or a year, it may be desirable to remove them, reclean by procedures described above and if needed, reimpregnate them with catalyst.

As mentioned above, the catalyst coated hot metal surfaces of the instant invention are useful in any process in which a textile coated with an organic material is heated to elevated temperatures. This will include use in heat setting ovens, processes in which fabric is coated and the coating cured, calendaring rolls, hot stretching ovens for tire cords, to name but a few. The invention is obviously useful for fiber manufacture, when high temperature treatment is necessary to induce stretching, setting, shrinking or crimping. The invention is especially applicable to the production of melt-spun fibers, since the heat treatment is often necessary in their manufacture yet excessive temperatures must be avoided due to their melt sensitivity. Among this group are the polyamides (nylons), the polyesters such as the polymethylene terephthalates and the polyolefins such as polypropylene.

EXAMPLE I The melt-spinning and drawing process disclosed by AFN. Good in U.S. Pat. No. 3,311,691 is used in this example. In accord with the process therein disclosed, poly (hexamethylene adipamide) is melted, extruded through spinneret orifices to form a 210 filament yarn and the filaments are cooled and forwarded to feed rolls 2, 3 as shown in the drawing of the Good patent. Prior to contacting feed rolls 2, 3, a lubricating finish of the type described by Coats in U.S. Pat. No. 3,248,258 is applied to the threadline. This finish deposits about 1.5% (based on wt. of yarn) oil and other nonvolatile organic material on the running threadline.

After feed rolls 2, 3, the filaments are snubbed and drawn over pin 4 in the first drawing stage, pulled by draw rolls 5, 6. The filaments then pass in helical wraps around hot pipe 7. where second-stage drawing occurs. The filaments then pass into hot chest 10, where they are annealed at constant length while passing in 15 wraps around driven rolls 12, 13. Rolls 12 and 13 are 6% inches in diameter and have a face length (in the axial direction), on which the yarn runs, of 9% inches. They have been given a coating of Cr O in accord with the teachings of England et al. in U.S. Pat. No. 3,080,134 which provides them with a hard ceramic coating characterized by rounded surface nodules having a surface roughness in the range of to 250 rrns microinches. Some of the rolls used in the test have not been used subsequent to applying the ceramic coating; others, which have been used, are furnace-cleaned by the procedure described above. Prior to the test, the rolls are treated as follows.

Treating solution A is prepared by dissolving 16.8 gm. platinum diamminedinitrite [Pt(NH (NO- in 500 ml. of dilute ammonium hydroxide (1 part of 28% NH Ol-l reagent solution to two parts water, by vol.), at a temperature of about 70C. The platinum compound is converted to the tetrammine complex, a)4( 2)2- Treating solution B is prepared by mixing 22.5 gm. hydrazine hydrate, H N'NH 'H O with 450 ml. water.

Equal volumes of solutions A and B are mixed and about 20 m1. of the mixture is applied to the yarn contacting surface of each roll while in the temperature range of 70 to C. The coating is carefully applied to the entire surface, coating from top to bottom. The rolls are then heated in an oven for 1 hr. at 200C. After cooling to 7080C., a second application of about 20 ml. of the catalyst solution is applied, followed by oven heating. Each roll has a deposit of about 0.4 gm. platinum. The rolls may be stored for subsequent use. For the present test, they are installed in a hot chest similar to 10 (rolls 12, 13).

For the purpose ofthis test, the hot chest is operated at a temperature of 210C. Yarn residence time in the hot chest is about 0.3 sec. Yarn of excellent quality is produced for a period of 30 days, without any roll cleaning. The test is discontinued in order to return to conventional production procedures.

In contrast, conventionally produced yarn from an adjacent spinning position, (on which no catalyst was used), required that the hot chest rolls be cleaned twice a week to maintain good yarn quality.

EXAMPLE ll When the test of Example I is repeated on a full spinning machine basis, starting with rolls newly coated with Cr Oa, producing 1260 denier, 210 filament yarn and using a hot chest temperature of 210C., good quality yarn is produced for 5 months, without interm ediate roll cleaning and essentially without broken filaments due to finish deposits on the rolls. In contrast, normal production of yarn without the catalyst, required roll cleaning twice a week.

What is claimed is:

1. A process for cleaning a movable surface characterized by irregular rounded surface nodules having interstices between the nodules to prevent accumulation of deposits of organic oxidizable material when a moving textile filamentary structure bearing a coating of finish containing oxidizable organic components is contacted by said surface moving at the same speed as said structure at elevated temperatures in the presence of oxygen, said process comprising: applying to said surface a solution of soluble catalyst metal salt and a reducing agent; heating said surface to dry and reduce the metal catalyst salt to a catalytic amount of finelydivided metal particles in the interstices; moving said surface; and contacting said moving surface with a textile filamentary structure of synthetic polymer moving at the same speed as said surface, said structure bearing a coating of finish containing oxidizable organic components, in the presence of oxygen and at a temperature of from about 100C. up to the melting point of the synthetic polymer whereby said oxidizable organic components are oxidized.

2. The process as defined in claim 1, said surface having a roughness of from about 70 to about 250 root mean square microinches.

3. The process as defined in claim 2, said applying and heating steps being repeated until the density of said catalyst particles on said surface is in the range of from about 0.03 to about 0.5 gm. per square foot.

4. The process as defined in claim 1, said catalyst being selected from the group consisting of platinum and palladium, said reducing agent being hydrazine hydrate.

5. The process as defined in claim 1, said contacting occurring in the presence of oxygen at a temperature of from about 210C. up to the melting point of the synthetic polymer. 

1. A PROCESS FOR CLEANING A MOVABLE SURFACE CHARACTERIZED BY IRREGULAR ROUNDED SURFACE NODULES HAVING INTERSTICES BETWEEN THE NODULES TO PREVENT ACCUMULATION OF DEPOSITS OF ORGANIC OXIDIZABLE MATERIAL WHEN A MOVING TEXTILE FILAMENTARY STRUCTURE BEARING A COATING OF FINISH CONTAINING OXIDIZABLE ORGANIC COMPONENTS IS CONTACTED BY SAID SURFACE MOVING AT THE SAME SPEED AS SAID STRUCTURE AT ELEVATED TEMPERATURES IN THE PRESENCE OF OXYGEN, SAID PROCESS COMPRISING: APPLYING TO SAID SURFACE A SOLUTION OF SOLUBLE CATALYST METAL SALT AND A REDUCING AGENT; HEATING SAID SURFACE TO DRY AND REDUCE THE METAL CATALYST SALT TO A CATALYTIC AMOUNT OF FINELY-DIVIDED METAL PARTICLES IN THE INTERSTICES; MOVING SAID SURFACE; AND CONTACTING SAID MOVING SURFACE WITH A FLEXIBLE FILAMENTARY STRUCTURE OF SYNTHETIC POLYMER MOVING AT THE SAME SPEED AS SAID SURFACE, SAID STRUCTURE BEARING A COATING OF FINISH CONTAINING OXIDIZABLE ORGANIC COMPONENTS, IN THE PRESENCE OF OXYGEN AND AT A TEMPERATURE OF FROM ABOUT 100*C. UP TO THE MELTING POINT OF THE SYNTHETIC POLYMER WHEREBY SAID OXIDIZABLE ORGANIC COMPONENTS ARE OXIDIZED.
 2. The process as defined in claim 1, said surface having a roughness of from about 70 to about 250 root mean square microinches.
 3. The procesS as defined in claim 2, said applying and heating steps being repeated until the density of said catalyst particles on said surface is in the range of from about 0.03 to about 0.5 gm. per square foot.
 4. The process as defined in claim 1, said catalyst being selected from the group consisting of platinum and palladium, said reducing agent being hydrazine hydrate.
 5. The process as defined in claim 1, said contacting occurring in the presence of oxygen at a temperature of from about 210*C. up to the melting point of the synthetic polymer. 